How are you going to deal with socks?
Not really a problem. To gain a lot of downvote power, short of creating a bunch of circle-upvote socks, you'd need to comment or write a lot, and longtime commenters like Eugine are generally easy to spot: everyone has idiosyncratic ideas, ways of phrasing things, writing styles, references and calculations... (without even getting into stylometrics). For example, if I were banned today and surfaced under another sock a month from now, I'd be spotted quickly - just look for the new account that uses lots of hyphens, semicolons, lists, quotations and paraphrases, etc in discussing topics like statistical & experimental methodology. Similarly, Eugine has a lot of idiosyncratic interests (global warming, the fall of the west, conservative family values and so on).
This is the same reason the worst special-interest trolls on Wikipedia didn't benefit much from socking: they had too clear a fingerprint in their arguments and writings.
True, but in my experience, Eugine's primary karma engine was karma-mining the Rationalist Quotes page; someone could simply commit to ONLY posting there, and build a pretty substantial resource pool rather quickly.
As previously discussed, on June 6th I received a message from jackk, a Trike Admin. He reported that the user Jiro had asked Trike to carry out an investigation to the retributive downvoting that Jiro had been subjected to. The investigation revealed that the user Eugine_Nier had downvoted over half of Jiro's comments, amounting to hundreds of downvotes.
I asked the community's guidance on dealing with the issue, and while the matter was being discussed, I also reviewed previous discussions about mass downvoting and looked for other people who mentioned being the victims of it. I asked Jack to compile reports on several other users who mentioned having been mass-downvoted, and it turned out that Eugine was also overwhelmingly the biggest downvoter of users David_Gerard, daenarys, falenas108, ialdabaoth, shminux, and Tenoke. As this discussion was going on, it turned out that user Ander had also been targeted by Eugine.
I sent two messages to Eugine, requesting an explanation. I received a response today. Eugine admitted his guilt, expressing the opinion that LW's karma system was failing to carry out its purpose of keeping out weak material and that he was engaged in a "weeding" of users who he did not think displayed sufficient rationality.
Needless to say, it is not the place of individual users to unilaterally decide that someone else should be "weeded" out of the community. The Less Wrong content deletion policy contains this clause:
Although the wording does not explicitly mention downvoting, harassment by downvoting is still harassment. Several users have indicated that they have experienced considerable emotional anguish from the harassment, and have in some cases been discouraged from using Less Wrong at all. This is not a desirable state of affairs, to say the least.
I was originally given my moderator powers on a rather ad-hoc basis, with someone awarding mod privileges to the ten users with the highest karma at the time. The original purpose for that appointment was just to delete spam. Nonetheless, since retributive downvoting has been a clear problem for the community, I asked the community for guidance on dealing with the issue. The rough consensus of the responses seemed to authorize me to deal with the problem as I deemed appropriate.
The fact that Eugine remained quiet about his guilt until directly confronted with the evidence, despite several public discussions of the issue, is indicative of him realizing that he was breaking prevailing social norms. Eugine's actions have worsened the atmosphere of this site, and that atmosphere will remain troubled for as long as he is allowed to remain here.
Therefore, I now announce that Eugine_Nier is permanently banned from posting on LessWrong. This decision is final and will not be changed in response to possible follow-up objections.
Unfortunately, it looks like while a ban prevents posting, it does not actually block a user from casting votes. I have asked jackk to look into the matter and find a way to actually stop the downvoting. Jack indicated earlier on that it would be technically straightforward to apply a negative karma modifier to Eugine's account, and wiping out Eugine's karma balance would prevent him from casting future downvotes. Whatever the easiest solution is, it will be applied as soon as possible.
EDIT 24 July 2014: Banned users are now prohibited from voting.